Univention Corporate Server 4.4 erratum 200 (bugfix)

This update addresses the following issue(s):
* The app badges icons in the App Center are replaced with new versions.
* A new App Setting "DockerUcrStyleEnv" was added to be able to deactivate
  passing environment variables into docker containers that are not in the 
  format of capital letters and underscores.
* An errata update caused the App Tab in the Users UMC module to not be
  visible. This update resyncs the listener so that the App Tab is visible
  again.